Zac, just curious... could you name one player in each of the following categories:
-great #1D Keith, Doughty, McDonough, Hedberg (between great and avg.), Karlsson (so elite offensively that he goes here), Subban,
-average #1D Weber, (arguably higher), Josi, Suter, Girardi, Chara (the way he's playing this year...maybe average), Carlson, Giordano (this year is a spot below) , Vlasic (arguably a spot above...regardless of where he plays he has always been solid to great...no down years), OEL (still don't think he's consistently proven himself), Ekblad (stud), Hammer
-bad/low level #1D Kronwall (always thought he was overrated), Letang, Burns (based on minutes...terrible defender),.
-great #2D Brodie, Klingberg, Seabs (when playing like he is now), Larsson, Hamonic, Alzner, Klingberg (if he keeps this up he likely belongs up top)
-avg #2D Brodin (somewhere between here and great), Markov (somewhere between here and great, this year he has been very good), Seth Jones, Gudbranson
-bad/ low level #2D - Leddy (considering his slot the last few years), Bouwmeester (between here and average), Campbell (migrates between here and average)
Better yet, here's a pretty comprehensive list on where I rank many of the top defenders. There are some teams, like the Toronto's, that are SO bad that you can't evaluate any one player really well. Some of the above may be 2nd pairing guys who I feel are a notch above, while a few are vice versa.
My criteria for a number one is someone who is either a pure shutdown defenseman against top competition, and or someone who is an elite offensive contributor who isn't an absolute sieve. The low ranking guys are those who are slotting on those pairings, and/or get the minutes (like a Letang) to rank as a "top pairing" guy.
Outside of those that are listed as bad/low level guys, I would take most of the other players above Seabs. They are either better, more consistent, or are younger/have a higher ceiling.
To be fair there are a lot of teams that don't have "#1 guys" even though they have to have guys that play those minutes. Seabs has been the 3rd best/most important Dman on this team for quite a while and despite having a solid year so far, he hasn't had consecutive great seasons for quite some time. If he could keep up this level of play I would be ecstatic with it, but his penchant for inconsistency, age, and body type make that extremely unlikely.